Re: [PATCH v2 1/2] perf expr: Add d_ratio operation

Jiri Olsa
2020-06-11T08:39:00Z

On Wed, Jun 10, 2020 at 04:58:22PM -0700, Ian Rogers wrote:
> d_ratio avoids division by 0 yielding infinity, such as when a counter
> doesn't get scheduled. An example usage is:
>
> {
> "BriefDescription": "DCache L1 misses",
> "MetricExpr": "d_ratio(MEM_LOAD_RETIRED.L1_MISS, MEM_LOAD_RETIRED.L1_HIT + MEM_LOAD_RETIRED.L1_MISS + MEM_LOAD_RETIRED.FB_HIT)",
> "MetricGroup": "DCache;DCache_L1",
> "MetricName": "DCache_L1_Miss",
> "ScaleUnit": "100%",
> }
>
> Signed-off-by: Ian Rogers <irogers@google.com>

Acked-by: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka

> ---
> tools/perf/tests/expr.c | 2 ++
> tools/perf/util/expr.l | 1 +
> tools/perf/util/expr.y | 14 ++++++++++++--
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> index 1cb02ca2b15f..c4877b36ab58 100644
> --- a/tools/perf/tests/expr.c
> +++ b/tools/perf/tests/expr.c
> @@ -39,6 +39,8 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
> ret |= test(&ctx, "1+1 if 3*4 else 0", 2);
> ret |= test(&ctx, "1.1 + 2.1", 3.2);
> ret |= test(&ctx, ".1 + 2.", 2.1);
> + ret |= test(&ctx, "d_ratio(1, 2)", 0.5);
> + ret |= test(&ctx, "d_ratio(2.5, 0)", 0);
>
> if (ret)
> return ret;
> diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
> index f397bf8b1a48..298d86660a96 100644
> --- a/tools/perf/util/expr.l
> +++ b/tools/perf/util/expr.l
> @@ -100,6 +100,7 @@ symbol ({spec}|{sym})+
> }
> }
>
> +d_ratio { return D_RATIO; }
> max { return MAX; }
> min { return MIN; }
> if { return IF; }
> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
> index bf3e898e3055..fe145344bb39 100644
> --- a/tools/perf/util/expr.y
> +++ b/tools/perf/util/expr.y
> @@ -10,6 +10,14 @@
> #include "smt.h"
> #include <string.h>
>
> +static double d_ratio(double val0, double val1)
> +{
> + if (val1 == 0) {
> + return 0;
> + }
> + return val0 / val1;
> +}
> +
> %}
>
> %define api.pure full
> @@ -28,7 +36,7 @@
> %token <num> NUMBER
> %token <str> ID
> %destructor { free ($$); } <str>
> -%token MIN MAX IF ELSE SMT_ON
> +%token MIN MAX IF ELSE SMT_ON D_RATIO
> %left MIN MAX IF
> %left '|'
> %left '^'
> @@ -64,7 +72,8 @@ other: ID
> }
> |
> MIN | MAX | IF | ELSE | SMT_ON | NUMBER | '|' | '^' | '&' | '-' | '+' | '*' | '/' | '%' | '(' | ')' | ','
> -
> +|
> +D_RATIO
>
> all_expr: if_expr { *final_val = $1; }
> ;
> @@ -105,6 +114,7 @@ expr: NUMBER
> | MIN '(' expr ',' expr ')' { $$ = $3 < $5 ? $3 : $5; }
> | MAX '(' expr ',' expr ')' { $$ = $3 > $5 ? $3 : $5; }
> | SMT_ON { $$ = smt_on() > 0; }
> + | D_RATIO '(' expr ',' expr ')' { $$ = d_ratio($3,$5); }
> ;
>
> %%
> --
> 2.27.0.278.ge193c7cf3a9-goog
>